-- KarlinBark - 21 July 2004
Goals for the test

Can humans distinguish between varying skin stretch magnitudes?
Specifically, what range of magnitudes can be felt on the human arm/shoulder/etc Apply various minimal/maximum forces to the skin and find the minimum force necessary to elicit a response, find the maximum force before the user feels it is painful

What is the JND of tangential forces applied to the skin? (~7% Weber Fraction according to Tan. et al, MIT 1994) Um...I think that a possible test is to give a pair of forces and ask the user to compare and distinguish which one was larger/smaller. Perhaps this can give an idea of what the sensitivity of the user is as well. (can the user distinguish a 0.1 N difference in force, or 0.5 N difference, etc)

What range of forces do humans describe as a 'low' force? 'medium' force? 'high' force? Give the user a minimum and maximum force, then give forces that vary in between and ask them how they perceive each force.

Another test is to set a low/med/high force. For example, set 0.1 N as low, 0.5 N as medium, and 0.7 N as high. Then, give the user various forces between 0.1 and 0.7 N and ask them what they perceive. I suspect that if you give a user a standard low force, anything that is higher than that, they will perceive as a medium force. So I expect the range described as being a 'medium' force to be the greatest.

Testing various skin stretch pain thresholds on myself ? On the back of the hand, I can withstand about 0.6 N of pull force, and on the forearm, I can withstand about 0.4 N of force. I suspect that a variation of 0.1 N might be distinguishable, but anything smaller than that will be difficult for people to differentiate.

Lowest force possible, 0.139 N on the oz. spring scale.

Nevermind, all these numbers are all wrong, since the scale we were using was not the same.